Multi-spindle CNC lathe

ABSTRACT

A multi-spindle CNC lathe comprises a frame assembly mounted on a base and including spaced apart, rigidly interconnected subframes defining spaced, parallel alignment surfaces. A plurality of spindles each includes a collet for rotating a stock about a spindle axis. An indexing mechanism positions the spindles in alignment with stations located at equally spaced intervals about a central axis. Internal tool slides mounted on the alignment surface of one of the subframes each comprise a servo mechanism for advancing and retracting a cutting tool along a work station axis. External tool slides mounted on the alignment surface of the other subframe each comprise a first servo mechanism for advancing and retracting a cutting tool toward and away from the work station axis and a second servo mechanism for selectively moving the cutting tool back and forth along a path extending parallel to the work station axis.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a continuation application under 37 C.F.R. §1.60 of applicationSer. No. 09/283,595 filed Apr. 1, 1999, now abandoned, which is acontinuation application of application Ser. No. 09/044,353 filed Mar.19, 1998, abandoned, which is a continuation application of applicationSer. No. 08/869,047, filed Jun. 4, 1997, now U.S. Pat. No. 5,918,514,which is a continuation application of application Ser. No. 08/514,734,filed Aug. 14, 1995, now U.S. Pat. No. 5,676,030.

TECHNICAL FIELD

This invention relates generally to machine tools, and more particularlyto a multi-spindle CNC lathe that is particularly adapted for use inconjunction with JIT and SPC manufacturing philosophies.

BACKGROUND AND SUMMARY OF THE INVENTION

Machine tools, including drills, lathes, milling machines, grinders andother finishing machines, and more complex devices such as screwmachines, are all characterized by a common objective: the manufactureof large numbers of identical finished parts under conditions of extremeaccuracy and maximum economy. As such, interest in and development ofmachine tools has paralleled the advance of the industrial revolution.

Traditionally, machine tools were operated by machinists who were amongthe most highly skilled and the most highly paid of all workers. Morerecently, however, machine tools have been adapted to a procedure knownas computer numeric control, or CNC, whereby the operation of machinetools is regulated by computers or other programmable controllers. Inaccordance with the CNC technique, the dimensions, surface finishes, andother characteristics of the part to be manufactured are supplied in theform of sequential operating instructions which are utilized by the CNCdevice to regulate the operation of the machine tool. This allows thecompletion of finished parts with more uniformity and more rapidity thanhas ever been possible heretofore.

The adaptation of single spindle lathes, milling machines, and similardevices to CNC techniques has largely been successful. However, in thecase of multi-spindle machine tools, previous attempts at automationhave largely comprised adapting the cams, gears, and other componentscomprising such machines to servo control. Perhaps because the approachhas been one of adapting old designs to new techniques, the effort todate at automating the operation of multi-spindle lathes by means of CNCoperation has largely been unsuccessful.

The present invention comprises a multi-spindle lathe which is entirelyadapted for CNC operation. In accordance with the broader aspects of theinvention, a plurality of spindles are positioned at spaced points abouta central axis. Each spindle has a collet which receives a length ofstock and rotates the stock about a spindle axis. An indexing mechanismis provided for selectively positioning the spindles at work stationslocated at equally spaced points about the central axis.

Each work station comprises an internal tool slide adapted to receive acutting tool and to advance the cutting tool toward and away from therotating stock under the action of a servo mechanism. An external toolslide is also provided for each work station and is adapted to advance acutting tool both toward and away from and parallel to the axis ofrotation of the stock. At each work station the stock is turned ratherthan formed, meaning that the cutting tools of the individual workstations may be utilized to perform a variety of quite distinctmachining operations.

The multi-spindle CNC lathe of the present invention is readily adaptedfor use in conjunction with both the Just In Time (JIT) and theStatistical Process Control (SPC) manufacturing philosophies. Inaccordance with JIT, only the exact number of piece parts necessary tocomplete a particular assembly operation are ordered at any one time.This eliminates the investment in inventory which is necessary whenlarge numbers of piece parts are ordered simultaneously, and alsoeliminates the possibility that previously ordered parts will becomeobsolete due to a change in design. The machine tool of the presentinvention is adapted to JIT because the economic batch is smaller. Thisis because machine tools incorporating the invention do not require thechanging of the cutting tools utilized at the various work stations inorder to change the nature of the piece parts being manufactured, andbecause set up time is reduced dramatically.

In accordance with SPC, completed piece parts are compared with apredetermined standard with a view towards maintaining the dimensions ofeach part at the center of the tolerance range. If the dimensions of theparts being manufactured begin to vary from the center of the tolerancerange, due to cutting tool wear or otherwise, adjustments in themanufacturing process are immediately instituted in order to maintaintolerances. SPC is easily practiced in the machine tool of the presentinvention since all of the cutting tools are positioned by servomechanisms which are in turn under computer numeric control.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete understanding of the invention may be had by referenceto the following Detailed Description, when taken in conjunction withthe accompanying Drawings wherein:

FIG. 1 is a front view of a multi-spindle CNC lathe incorporating thepresent invention;

FIG. 2 is a front view of the base of the multi-spindle CNC lathe ofFIG. 1 in which certain parts have been broken away more clearly toillustrate certain features of the invention;

FIG. 3 is a top view of the base of FIG. 2;

FIG. 4 is a longitudinal sectional view illustrating the frame andcertain operating components of the multi-spindle CNC lathe of FIG. 1;

FIG. 5 is an enlargement of a portion of FIG. 4;

FIG. 6 is a front view of the multi-spindle CNC lathe of the presentinvention similar to FIG. 1 in which the covers of the apparatus havebeen removed;

FIG. 7 is an illustration of certain components of the multi-spindle CNClathe of FIG. 6 taken along the line 7--7 of FIG. 6;

FIG. 8 is an illustration of certain components of the multi-spindle CNClathe of FIG. 6 taken along the line 8--8 in FIG. 6;

FIG. 9 is an enlargement of a portion of FIG. 8;

FIG. 10 is a further illustration of certain components shown in FIG. 9;

FIG. 11 is a side view of one of the internal slide assemblies of themulti-spindle CNC lathe of FIG. 6 in which certain components have beenbroken more clearly to illustrate certain features of the invention;

FIG. 12 is an illustration of certain components of the multi-spindleCNC lathe of FIG. 6 taken along the line 12--12 of FIG. 6;

FIG. 13 is an illustration of one of the external slide assemblies ofthe multi-spindle CNC lathe of the present invention;

FIG. 14 is a sectional view taken along the line 14--14 of FIG. 13;

FIG. 15 is a sectional view taken along the line 15--15 of FIG. 14further illustrating the external slide assemblies of the multi-spindleCNC lathe of the present invention;

FIG. 16 is longitudinal sectional view further illustrating the externalslide assemblies of the multi-spindle CNC lathe of the presentinvention;

FIG. 17 is a sectional view taken along the line 17--17 of FIG. 13;

FIG. 18 is an enlargement of a certain portion of the apparatusillustrated in FIG. 17;

FIG. 19 is an illustration of certain of the components of themulti-spindle CNC lathe of the present invention taken along the line19--19 of FIG. 6.

FIG. 20 is an illustration of one of the spindles of the multi-spindleCNC lathe of the present invention showing the component parts thereofin a first orientation;

FIG. 21 is view similar to FIG. 20 showing the component parts of thespindle in a second orientation;

FIG. 22 is an illustration similar to FIG. 20 showing the componentparts thereof in a third orientation;

FIG. 23 is a sectional view illustrating the glut actuator of themulti-spindle CNC lathe of the present invention;

FIG. 24 is a sectional view taken along the line 24--24 of FIG. 25 andillustrating the spindle carrier of the multi-spindle CNC lathe of thepresent invention;

FIG. 25 is an end view of the spindle carrier of the multi-spindle CNClathe of the present invention;

FIG. 26 is an enlarged illustration of one of the castings comprisingthe frame of the present invention;

FIG. 27 is an illustration of the one of the stock carrying tubes of themulti-spindle CNC lathe of the present invention;

FIG. 28 is an enlarged sectional view further illustrating the stockcarrying tubes of the multi-spindle CNC lathe of the present invention;

FIG. 29 is a front view illustrating the stock carriage assembly of themulti-spindle CNC lathe of the present invention;

FIG. 30 is a partial sectional view illustrating the indexing mechanismof the multi-spindle CNC lathe of the present invention;

FIG. 31 is a partial sectional view illustrating a tool holder accessaryuseful in conjunction with the multi-spindle CNC lathe of the presentinvention;

FIG. 32 is a further illustration of the three point mounting system ofthe frame of the multi-spindle CNC lathe of the present invention;

FIG. 33 is a still further illustration of the three point mountingsystem of the frame of the multi-spindle CNC lathe of the presentinvention;

FIG. 34 is a perspective view illustrating the operation of themulti-spindle CNC lathe of the present invention; and

FIG. 35 is a perspective view further illustrating the operation of themulti-spindle CNC lathe of the present invention.

DETAILED DESCRIPTION

Referring now to the Drawings, and particularly to FIG. 1 thereof, thereis shown a multi-spindle CNC lathe 50 incorporating the presentinvention. The lathe 50 includes a base 52 which also serves as acoolant reservoir. A housing 54 extends upwardly from the base 52 andserves to enclose and protect both the mechanical components and theproduction components of the multi-spindle CNC lathe 50.

A computer numeric control (CNC) system 56 is located at one end of thehousing 54. The CNC system 56 is preferably of the type sold by GeneralElectric Company as and identified by that company as the Power MateMotion Control Systems, and may include a computer monitor screen 58and/or a plurality of status lights 60. A keyboard 62 may be used toeffect computer control over the operation of the lathe 50. The CNCsystem 56 may further include a conventional control panel 64.

The housing 54 of the multi-spindle CNC lathe 50 further includes asliding access door 66. The door 66 is slidably supported on a slideways68 and is provided with a viewing window 70. The production componentsof the multi-spindle CNC lathe 50 are located behind the door 66 when itis in the closed position as illustrated in FIG. 1, and are observablethrough the viewing window 70 thereof.

A hinged door 72 provides access to the mechanical components of thelathe 50. Access ports 74 are normally enclosed by removable covers 76.A cover 78 enclosing the stock carriers of the lathe 50 extendsleftwardly (FIG. 1) from the main portion of the housing 54.

Referring now to FIGS. 2 & 3, the base 52 of the multi-spindle CNC lathe50 is shown in greater detail. The base 52 is comprised entirely ofsteel plates which are interconnected by welding. The base 52 isprovided with a plurality of mounting blocks 80 and a plurality ofmounting holes 82 which function to attach the operating components ofthe lathe 50 to the base 52.

In addition to supporting and locating the operating components of thelathe 50, the base 52 serves as a coolant reservoir. Coolant enteringthe base 52 is initially contained by a plate 84 which defines a coolantlevel 86. Chips caused by operation of the multi-spindle CNC lathe 50enter the base 52 through a port 88 and are received on a chip conveyor90 located above the plate 84. The conveyor 90 transports the chips outof the base 52, whereupon the chips fall into a chip receiving container92 under the action of gravity.

During operation of the lathe 50, coolant constantly flows over a lip 94located at one end of the plate 84. From the lip 94 the coolant flowsinto and through a basket 96 which functions to strain the coolant,thereby removing any debris which is not transported out of the base 52by the chip conveyor 90. Preferably, two baskets 96 are employed in theoperation of the lathe, one located in the working position as definedby a bracket 98 and the other positioned on a drain platform 100 whichallows coolant to drain out of the basket 96 prior to the removal ofdebris therefrom. Coolant flowing through the basket 96, located in theworking position as defined by the bracket 98, flows along a pathdefined by the arrows 102 and is returned to the operating components ofthe lathe 50 by a pump (not shown) which withdraws the coolant from thebase at aperture 103. This flow path maintains uniform temperature ofthe base 52 and eliminates static spots which can cause the coolant tobecome rancid.

As is best shown in FIG. 4, the multi-spindle CNC lathe 50 includes aframe 104 comprising an important feature of the invention. The frame104 include precision castings 106 and 108 which function to support andalign the operating components of the lathe 50. The casting 106comprises opposed walls 110 and 112, and the casting 108 comprisesopposed walls 114 and 116.

The walls 110 and 112 of the casting 106 define opposed surfaces 120 and122, respectively. The surfaces 120 and 122 are ground flat and smoothutilizing Blanchard grinding or a functionally equivalent process. Thesame procedure assures precise parallelism between the surfaces 120 and122. The walls 114 and 116 comprising the casting 108 define opposedsurfaces 124 and 126 which are identically processed, and are thereforeequally flat, smooth, and parallel. The surfaces 122 and 124 define thealignment surfaces of the frame 104 of the lathe 50.

The frame 104 further comprises four tie rods 128 which are matchmachined in order to maintain precise parallelism between the surface122 of the casting 106 and the surface 124 of the casting 108. Each tierod 128 includes an elongate central portion 130 extending to reduceddiameter portion 132 which in turn extends to a threaded end member 134.At the bottom of the casting 108, a bushing 136 is mounted on eachreduced diameter portion 132 and is received in aligned apertures 138formed in the casting 108 and an aperture 140 formed in a mounting block142.

A plurality of nuts 144 are each threadedly engaged with a threaded endportion 134 of one of the tie rods 128. The nuts 144 engage washers 146which in turn engage compression members 148. Thus, upon precisetightening of the nuts 144, using, for example, a torque wrench, thecastings 106 and 108 comprising the frame 104 are securely positionedwith respect to one another.

At the upper ends of the castings 106 and 108, and at the lower end ofthe casting 106, the reduced end portions of the rods 128 extend throughapertures 138' formed in the castings 106 and 108. Likewise, the nuts144 engage the washers 146 which directly engage the castings 106 and108.

The casting 106 is supported on a mounting block 142' which bridgesacross the frame 104 and is supported by the mounting blocks 80 thereof.

The mounting blocks 142 and 142' are secured to the base 52 by pluralityof threaded fasteners 152. The mounting blocks 142 engage the mountingblocks 80 of the base 52 to precisely position the frame 104 withrespect thereto. An important aspect of the present invention comprisesthe use of the three point mounting system comprising the two mountingblocks 142 and 142' to mount the frame 104 on the base 52. By this meansany possibility of tipping, wobbling, or misalinement between the base52 and the frame 104 is eliminated.

The three point mounting system which supports the frame 104 on the base52 is further illustrated in FIGS. 32 and 33. Each mounting block 142engages an individual mounting block 80 of the base 52 to support thecasting 108 at two parts. In contrast, the mounting block 142' bridgesbetween two mounting blocks 80 and supports the casting 106 at a single,central point, thereby providing three point support for the frame 104.A pin 150 extends through aligned apertures 138 in the casting 106, andan aperture 103 formed in the center of the mounting block 142'. A nut144 is threadably engaged within the end portion 134 of the pin 150, andengages a washer 146 which engages a compression member 148.

A spindle drive motor 154 is mounted at one end of the frame 104 of themulti-spindle CNC lathe 50. The spindle drive motor is preferably avariable speed alternating current electric motor. The motor 154 issupported by a motor mounting adaptor 156 which is in turn supported bya bearing housing 158. The bearing housing 158 is secured to the wall110 of the casting 106 of the frame 104 by a plurality of threadedfasteners 160.

The motor 154 has an output shaft 162 which extends to a flexiblecoupling 164. The flexible coupling 164 in turn drives a spindle driveshaft 166. The drive shaft 166 is rotatably supported by a bearing 168which is retained in the bearing housing 158 by an end plate 170 that isin turn secured by threaded fasteners 172. A spacer 174 and a lock nut176 complete the drive shaft/bearing assembly.

Referring to FIGS. 4 and 5, the drive shaft 166 extends through a piston180 which is secured to a tubular ram 182 by a plurality of threadedfasteners 183. The piston 180 is mounted in a cylinder 184 which islocated relative to the wall 112 of the casting 106 by a hardenedprecision dowel pin 186 and is secured to the wall 112 by a plurality ofthreaded fasteners 188. A first hydraulic fluid chamber 190 is definedat one end of the piston 180 and is isolated by a plurality of seals192. The chamber 190 is closed by an end plate 194 which is secured tothe cylinder 184 by a plurality of threaded fasteners 196. The end plate194 is provided with a hydraulic fluid inlet and outlet port 198.

A second hydraulic fluid chamber 200 is located at the opposite end ofthe piston 180 and is isolated by a plurality of seals 202. The chamber200 is provided with a hydraulic fluid inlet and outlet port 204 formedin the cylinder 184. Thus, upon selective application of hydraulicpressure to one of the chambers 190 or 200 and the simultaneous releaseof hydraulic pressure from the opposite chamber, the piston 180 and thetubular ram 182 are caused to move longitudinally relative to thecylinder 184.

The end of the tubular ram 182 remote from the piston 180 is providedwith a flange 206. A retaining ring 208 engages the flange 206, and aplurality of threaded fasteners 210 secure the retaining ring to anadapter 212. The adapter 212 supports a bearing 216 which rotatablysupports the shaft 166. The threaded fasteners 210 and the retainingring 208 also function to secure the tubular ram 182 to a spindlecarrier assembly 218.

The working components of the multi-spindle CNC lathe 50 illustrated inFIGS. 6 through 19, inclusive. As is clearly shown, for example, inFIGS. 7, 8, and 9, the particular multi-spindle CNC lathe 50 illustratedin the Drawings and described herein comprises an eight spindle device.However, as will be appreciated by those skilled in the art, the presentinvention is readily adapted for use in conjunction with multi-spindleCNC lathes having any desired number of spindles as may be dictated bythe requirements of a particular application of the invention.

Internal slide assemblies 220 comprising the multi-spindle CNC lathe 50are illustrated in FIGS. 7, 8, 9, 10, and 11, inclusive. Referringparticularly to FIGS. 7 and 11, each internal slide assembly 220includes a motor 224 which is secured to a motor mounting plate 226 by aplurality of threaded fasteners 228. The motor mounting plate 226 is inturn secured to a mounting plate 230 by a plurality of threadedfasteners 232. The mounting plate 230 is in turn secured to the wall 110of the casting 106 comprising the frame 104 by a plurality of threadedfasteners 234.

The motor 224 has an output shaft 236 which is secured to a drive pulley238. A drive belt 240 extends around the drive pulley 238 and a drivenpulley 242. The driven pulley 242 is mounted on a spacer 244 which is inturn secured to an adapter 246. Thus, upon operation of the motor 224,the adapter 246 is rotated under the action of the motor 224, the outputshaft 236, the drive pulley 238, the belt 240, the driven pulley 242,and the spacer 244.

The adapter 246 is rotatably supported on the wall 110 by bearings 248.The bearings 248 are supported in a bearing housing 250 by a pluralityof threaded fasteners 252 which extend through the mounting plate 230. Aball nut 254 is mounted on the adapter 246 and is secured thereto by aplurality of threaded fasteners 256.

A ball screw 258 extends through and is operatively engaged with theball nut 254. The ball screw 258 is secured against rotation relative tothe ball nut 254. Thus, upon actuation of the motor 224 to rotate theadapter 246 and the ball nut 254, the ball screw 258 is selectivelyextended or retracted.

A target adapter 260 extends from one end of the ball screw 258 andsupports a target 262. A sensor bracket 264 is secured to the mountingplate 226 by a plurality of threaded fasteners 266. Proximity sensors268, 270, and 272 are mounted on the bracket 264. Upon the alignment ofthe target 262 therewith, the proximity sensors 268, 270, and 272 areactuated to generate a signal indicative of the positioning of the ballscrew 258 relatively to the frame 104 of the lathe 50. Proximity sensor270 is indicative of the normal positioning of the ball screw 258,proximity sensor 272 is indicative of the fully retracted positioning ofthe ball screw 258, and proximity sensor 286 is indicative of the fullyextended position of the ball screw 258.

The motor 224 operates under control of the CNC system 56 to positionthe ball screw 258. The outputs of the proximity sensors 268, 270, and272 are directed to the CNC system 56, which in turn operates the motor224 to properly position the ball screw 258 in accordance with theprogram being run.

The ball screw 258 extends through a ball screw boot 274. The boot 274is secured to the wall 112 of the casting 106 of the frame 104 by aplurality of threaded fasteners 276. At the distal end of the boot 274there is provided a rod wiper 278.

The end of the ball screw 258 remote from the target adapter 260 isprovided with a threaded portion 280. A pusher bracket 282 is secured tothe end of the ball screw 258 by a nylon insert lock nut 284 threadablyengaged with the threaded portion 280 of the ball screw 258. A flatwasher 286 is located between the pusher bracket 282 and the ball screw258.

A slide body 292 is secured to the pusher bracket 282 for reciprocationunder the action of the ball screw 258 and the ball nut 254 which is inturn actuated by the motor 224 under the control of the CNC system 56.Drive keys 294 are mounted at one end of the slide body 292 and issecured thereto by a plurality of threaded fasteners 296. The slide body292 is provided with a conventional central bore 298 and is adapted toreceive a conventional tool holder, which in turn receives aconventional tool such as a drill, reamer, etc.

Those skilled in the art will appreciate the fact that the slide body292 and tool holder received therein comprise static devices which areadapted to provide end working functions on rotating stock. The internaltool slide assembly 220 is also adapted for use with active slidecomponents adapted for performing end working functions such as tapping,profile work, etc. and also for performing the pick up function afterthe work piece has been severed.

FIG. 31 illustrates an active tool holder assembly 700 which may be usedin lieu of the passive tool holder assembly of FIG. 11 in the internalslide assembly of the multi-spindle CNC lathe 50 of the presentinvention, if desired. The tool collet holder assembly 700 includes atool holder receiver 702 which is rotatably supported on a sub-frame 704by bearings 706. A motor 708 has as output 710 which drives a drivepulley 712. A belt 714 extends around the drive pulley 712 and a drivenpulley 716 which is operatively connected to the tool holder receiver702. In the use of the apparatus 700, a conventional tool holder ispositioned in the bore 720 of the tool holder receiver 702. The toolholder in turn receives a conventional tool. By means of the motor 708,the tool is adapted for rotation as it is advanced toward and away fromthe rotating stock. By this means the tool may be utilized to provide,for example tapping of the stock.

Referring to FIG. 9, each slide body 292 has a pair of guide blocks 304secured thereto by threaded fasteners 306. The guide 304 blocks arereceived in correspondingly shaped, hardened and precision ground,guideways formed in a guide body 308 and defined by components 307 and314. Sliding movement of the guide blocks 304, and therefore the andslide bodies 292, is facilitated by the positioning of layers ofpolytetrafluroethylene 310 between the guide blocks 304 and thecorresponding guideways.

The construction of the guide body 308 will be best understood bysimultaneous reference to FIGS. 5 and 9. The component parts 307 of theguide body 308 comprising the guideways are secured to the cylinder 184by a plurality of threaded fasteners 312. The component parts 314 aresecured by a plurality of threaded fasteners 316. A cover plate 318 ismounted at the end of the guide body 308 remote from the piston 180 andis secured by a plurality of threaded fasteners 320.

Coolant is discharged from flexible nozzle assemblies 322 to the workingarea. The nozzle assemblies 322 are selectively mounted in dischargedapertures 324 provided in the cover plate 318. The apertures 324 extendto a passageway 326. Coolant is directed into the passageway 326 fordischarge from the flexible nozzle assemblies 322 through an inlet port328 formed in the cylinder 184.

Referring now to FIGS. 12 through 19, inclusive, the multi-spindle CNClathe 50 includes a plurality of external slide assemblies 330. Eachexternal slide assembly 330 is supported on the wall 114 of the casting108 of the frame 104 by a support bracket 332 which is secured to thewall 114 by a plurality of threaded fasteners 334. Each external slideassembly 330 is adapted to support and position a cutting tool 336relative to rotating stock. The external slide assemblies 330 functionto move cutting tools 336 both toward and away from the rotating stockand toward and away from the wall 114 of the frame 104, i.e., parallelto the stock.

Referring to FIGS. 13 and 15, each external slide assembly 330 includesa housing 340 which is guided by a circular guide 342 and a rectangularguide 344. The guide 342 is mounted on the housing 340 and is slidablysupported by bushings 343 mounted on the bracket 332. The guide 344 ismounted on the bracket 332 and is secured by threaded fasteners 335.

Referring to FIGS. 15 and 19, a motor 346 is mounted on a motor mountingplate 350 and is secured thereto by a plurality of threaded fasteners.The motor mounting plate 350 is in turn supported on a mounting plate352 by a plurality of threaded fasteners 354.

The motor 346 has an output shaft 356 which is connected to a drivepulley 358. The drive pulley 358 drives a belt 360 which in turn drivesa driven pulley 362. The driven pulley 362 is secured on a adapter 364by a spacer 366. The adapter 364 is rotatably supported on the wall 116by a bearing 368 which is mounted in a bearing housing 370. The bearinghousing 370 is secured in the plate 352 by a plurality of threadedfasteners 372.

A ball nut 374 is secured to the adapter 364 by a plurality of threadedfasteners 376. Thus, upon actuation of the motor 346 operating throughthe drive shaft 356, the drive pulley 358, the drive belt 360, anddriven pulley 362, the spacer 366, and the adapter 364, the ball nut 374is actuated to rotate relative to the wall 116. A ball screw 378 extendsthrough and is operatively connected to the ball nut 374.

A target adapter 380 is secured to one end of the ball screw 378 and hasa target 382 mounted on the distal end thereof. A plurality of proximitysensors 384, 386, and 388, are mounted on a support plate 390 which issecured to the motor mounting plate 350 by a plurality of threadedfasteners 392. When the target 382 is aligned with one of the proximitysensors 384, 386, or 388, a signal is generated indicative of thepositioning of the housing 340 of the external slide assembly relativeto the wall 114 of the frame 104.

The end of the ball screw 378 remote from the target adapter 380comprises a threaded end portion 394. The ball screw 378 is secured tothe housing 340 of the external slide assembly 330 by a nylon insertlock nut 396. Therefore, upon operation of the motor 346, the ball nut374 functions to actuate the ball screw 378 to locate the housing 340relative to the wall 114. Referring to FIG. 16, the housing 340 issupported for sliding movement toward and away from the wall 114 byguide members 342 and 344.

The motor 346 operates under control of the CNC system 56 to positionthe ball screw 378. The outputs of the proximity sensors 384, 386, and388 are directed to the CNC system 56 which in turn operates the motor346 to position the ball screw 378 in accordance with the program beingrun.

As is best shown in FIGS. 16 and 17, a motor 400 is mounted at the endof the housing 340 remote from the cutting tool 336. The motor 400 hasan output shaft 402 which is connected to a flexible coupling 404 whichis in turn connected to one end of a ball screw 406. The ball screw 406is rotatably supported by bearings 408 and 410 mounted in the housing340.

A ball nut 412 is mounted on and operatively connected to the ball screw406. The ball nut 412 is secured to a tool slide 414 which is slidablysupported in the housing 340 by a plurality of threaded fasteners 416.Thus, upon actuation of the motor 400 to rotate the ball screw 406, theball nut 412 functions to move the slide 414 and therefore the cuttingtool 336 inwardly and outwardly relative to the housing 340.

The motor 400 operates under control of the CNC system 56. The motor 400and the slide 414 have associated therewith a target and a plurality ofproximity sensors like the target 382 and the sensors 384, 386, and 388associated with the ball screw 378. The CNC system 56 receives signalsfrom the sensors to allow control over the positioning of the cuttingtool 336.

Referring particularly to FIG. 18, there is shown a quick disconnectcoupling for the cutting tool 336. The cutting tool 336 is supported ona threaded fastener 416 positioned within the slide 414. The cuttingforces resulting from engagement of the cutting tool 336 with rotatingstock are taken by a reaction block 418 which is secured to the slide414 by a threaded fastener 419. The threaded fastener 416 and thereforethe cutting tool 336 are normally secured in the position shown in FIG.18 by a retaining bar 420 having a ramp portion 422. A pin 424 ispositioned between the ramp portion 422 and the mounting bar 416 andfunctions to retain the threaded fastener 416 and therefore the cuttingtool 336 in place. A spring 426 normally retains the bar 420 in place.

A stop 428 is mounted in the housing 340 at the remote end of the slide414. When the slide 414 is fully retracted under the action of the ballnut 412 and the ball screw 406, the bar 420 engages the stop 428. Thisaction compresses the spring 426 thereby relieving the pressure imposedon the pin 424 by the ramp portion 422. This in turn allows the cuttingtool 336 and the threader fastener 416 to be disengaged from the slide414.

The multi-spindle CNC lathe 50 of the present invention further includesa plurality of spindles 430 of the type illustrated in FIGS. 20, 21, and22. Each spindle 430 is rotatably supported in the spindle carrier 218of FIG. 4 by bearings 432 and 434 and is retained therein by threadedfasteners 436 and 438.

Each spindle 430 comprises a main body portion 440 having a planet gear442 mounted thereon. Spacers 444 and 446 are interposed between theplanet gear 442 and bearings 432 and 434 respectively. A colletreceiving bore 448 extends through the main body 440 and a conventionalself-opening collet 450 is disposed therein. A conventional colletaligning mechanism 452 may be positioned at the collet receiving end ofthe bore 448. A driving key 454 assures proper alignment between thecollet and the spindle.

The spindles 430 of the present invention comprise a unique colletopening, collet closing, and collet releasing mechanism. A glut 456 isslidably supported on a glut guide 458 and includes a dog 460 whichengages a slot 462 formed in a collet actuator 464 mounted on thespindle 430. The collet actuator 464 includes a retainer 466 which issecured by threaded fasteners 468. A spring actuating member 470 isslidably supported within the main body 440 of the spindle 430. A springactuated retainer 472 is slidably supported on the spring actuator 470.

The collet locked position is illustrated in FIG. 20. At this point theglut 456 has been actuated to position the collect actuator 464 at itsextreme rearward position relative to the collet 450. A series of wedges474 have been forced downwardly. This action moves a slider 476rearwardly compressing compensating washers 478, whereby a length ofstock to be worked (not shown) is securely retained in the collet 450. Adog 480 on the spring actuated retainer 472 is disengaged from thespring retainer 466 whereby a plunger 482 is fully extended under theaction of a spring 484.

In FIG. 21 the glut 456 is actuated to move the collect actuator 464toward the planet gear 442. The wedges 474 move upwardly under theaction of the compensating washers 478 and centrifugal force. Theretainer 466 approaches but does not quite engage the dog 480, wherebythe plunger 482 remains in position. At this point the self-openingcollet 450 is released sufficiently to permit the repositioning of stockextending therethrough and/or to receive a new length of stock havingthe same dimensions as the previously engaged stock.

In FIG. 22 the glut 456 is actuated to move the collect actuator 464 toits extreme position. At this point the spring 484 is substantiallycompressed due to actuation of the plunger 482 by the spring actuatingmember 470 and the engagement of the dog 480 with the retainer 466. Thisaligns a detent 486 with a retaining ball 488 to allow the ball 488 tomove upwardly, thereby permitting the removal of the collet 450.

Collet removal is indicated when a different size or type of stock is tobe retained by the collet 450 for rotation by the spindle 430. Removalof the collet 450 may be effected either manually or automaticallythrough the use of conventional collet removal and replacementapparatus. FIG. 23 illustrates a glut actuator 490 useful in thepractice of the present invention to operate the dog 460 shown in FIG.20. The glut actuator 490 is mounted on the wall 116 of the casting 108and is supported thereon by a mounting plate 492 which is secured to thewall 116 by a plurality of threaded fasteners 494. A glut actuator 496is secured to a movable housing 498 which is slidably supported on aguide rod 500. The guide rod 500 is secured to the mounting plate 492 bya threaded fastener 502. A piston 504 is fixedly mounted on the guiderod 500, and is provided with seals 506. An inner piston 508 is slidablysupported on the guide rod 500 and is provided with seals 510. An outerpiston 512 is likewise slidably supported on the guide rod 500 and isprovided with seals 514.

The pistons 504, 508, and 512 divide the housing 498 into four chambers516, 518, 520, and 522. Hydraulic fluid inlet and outlet ports 526, 528,530, and 532 extend to the chambers 516, 518, 520 and 522, respectively.Chamber 516 is secured against leakage by seals 534, and chamber 522 issecured against leakage by seals 536.

It will thus be understood by those skilled in the art that byselectively admitting pressurized hydraulic fluid to one of the chambers516, 518, 520, and 522, and by simultaneously draining hydraulic fluidfrom the remaining chambers, the housing 498 and therefore the glutactuator 496 may be selectively located in any of four positionsrelative to the guide rod 500 and the chamber 516. In this manner theglut actuator 490 of FIG. 23 functions to position the dog 460 of FIG.20, thereby selectively engaging, disengaging, or releasing the collets450 of the multi-spindle CNC lathe 50 of the present invention. Thefourth position of the glut actuator 490 is used to allow indexing ofthe spindle carrier 218.

Referring to FIG. 19, the multi-spindle CNC lathe 50 is shown as havingeight gluts 456, eight glut guides 458, eight dogs 460, and eight glutactuators 490. This is to demonstrate the use of such components at anyof the work stations and in as many numbers as needed for the particularapplication of the invention. Usually, no more than two gluts and glutactuators will be needed.

The spindle carrier 218 of FIG. 4 is further illustrated in the FIG. 24.Multi-toothed coupling portion 540 having teeth 542 formed at equallyspaced intervals therearound is secured between opposed body portions544 and 546. Coupling portion 540 is aligned by means of a dowel 548 andis secured in place by means of threaded fasteners 550. The bodyportions 544 and 546 are in turn secured together by threaded fasteners552.

The spindle supporting bearings 434 illustrated in FIGS. 20, 21, and 22are received in a bearing receiving cavity 554 formed in body member546. The bearings 434 are secured in place by a plate 556 which isretained by the threaded fasteners 438. The bearings 432 as illustratedin FIGS. 20, 21, and 22 are received in a bearing receiving cavity 558formed in the body member 544. The bearings 432 are secured by a plate560 which is secured in place by the threaded fasteners 436.

Referring again to FIG. 24, the body portions 544 and 546 are preferablysecured in place prior to the machining of the bearing receivingcavities 554 and 558, thereby assuring precise alignment between thecavities. It will be appreciated that it is occasionally necessary todisassemble the body portions 544 and 546. To this end there is providedan alignment ring 562 having extended profile portions 564. The profileportions comprise segments of approximately 60 degrees which are in turnseparated by vacant segments of approximately 60 degrees. By means ofthe profile portions 564 of the alignment ring 562, the body portions544 and 546 of the spindle carrier 218 may be separated and reassembledwithout loss of alignment between the bearing receiving cavities 554 and558.

A sun gear 570 is rotatably supported within the spindle carrier 218.The sun gear 570 is rotatably supported by bearings 572 which areretained by a plate 574. The plate 574 is in turn retained by threadedfasteners 576.

The sun gear 570 has an internal spline 578 which engages in theinternal spline 579 of the drive shaft 166 in FIG. 4. In this manner thesun gear is rotated under the action of the spindle drive motor 154. Thesun gear 570 engages the planet gears 442 of the spindles 430, wherebythe motor 154 functions to rotate the spindles at a predetermined speed.

The spindle carrier 218 is secured to the tubular ram 182 by means ofthe threaded fasteners 210 which engage complementary threaded apertures580 formed in the body portion 546. Thus, upon actuation of the piston180, the positioning of the spindle carrier 218 is shiftedlongitudinally relative to the frame 104.

Referring to FIG. 26, the casting 108 comprising the frame 104 has amulti-toothed coupling portion 582 secured therein by threaded fasteners586. The coupling portion 582 comprises a plurality of teeth 588 whichare inverse to the teeth 542 of the coupling portion 540 of the spindlecarrier 218. Thus, when the piston 180 is actuated to move the ram 182toward the casting 108, the teeth 542 of the spindle carrier 218 engagethe teeth 588 of the coupling portion 582 on the casting 108 to securethe spindle carrier 218 against rotation relative to the frame 104 ofthe multi-spindle CNC lathe 50. Conversely, when the piston 180 isactuated to move the ram 182 away from the casting 108 the teeth 542 onthe spindle carrier 218 are disengaged from the teeth 588 of thecoupling portion 582 on the casting 108, whereupon the spindle carrier218 is adapted for indexing relative to the frame 104 of the lathe 50.

The frame 104 is provided with a bearing member 590. The bearing member590 has a precisely machined internal surface 592 which rotatablysupports the spindle carrier 218 for indexing. To this end the lowersegment of the bearing surface 216 is provided with a layer ofpolytetrafluroethylene 594 to facilitate rotation of the spindle carrier218 relative to the bearing member 590

The multi-spindle CNC lathe 50 is provided with a plurality of stockcarrier assemblies 600 which are best illustrated in FIGS. 27 and 28.Each stock carrier assembly 600 includes an inner stock carrying tube602 which extends through one of the spindles 430 and is supportedtherein for rotation with the collet 450 received in and rotated by thespindle 430. Each tube 602 is secured to a nut 604 which is threadedlyengaged with the spindle 430, thereby securing the tube 602 for rotationwith the collet 450. The use of a stock carrying tube adapted forrotation with the stock received therein comprises an important featureof the present invention and is a significant departure from the priorart.

Throughout a significant portion of its length the tube 602 extendsthrough a stationary tube 606. The tube 606 is provided with aconventional closure 608 located at the end thereof remote from thespindle 430. The particular closure 608 illustrated FIG. 27 is of thebayonet variety and is provided with a handle 610 which is movedinwardly to release the closure 608 for the insertion of stock into andthrough the tubes 606 and 602. At all other times the closure 608remains positioned as shown in FIG. 27 to seal the interior of the tube606 against leakage of coolant therefrom.

The rotating tube 602 has a plurality of apertures 612 formed therein topermit the flow of coolant out of the tube 602 into the tube 606. Thetube 606 extends to a seal 614 which prevents leakage of coolant fromthe end of the tube 606 remote from the closure 608. A secondary seal616 is mounted on the seal 614 and extends along the tube 602 further toprevent leakage of coolant.

Each tube 606 is further provided with fixtures 618 and 620 whichfunction to admit coolant into the tube 606. Whenever it is desired toadvance the position of the stock located within and rotating with thetube 602, the pressure of the coolant within the tube 606 is increased.It will be understood that one end of the stock is situated within theassembly comprising the tubes 602 and 606, and is therefore subject tothe application of an endwise force resulting from the increase incoolant pressure. However, the opposite end of the stock is situatedwithin the collet and is therefore not subject to the increased pressureof the coolant within the tubes 602 and 606. By this means there isprovided an endwise force on the stock which pushes the stock throughthe collet 450 without requiring the use of independent stock advancingmechanisms. The presence of the coolant within the tubes 602 and 606also provides significant vibration damping and noise reduction ascompared with prior art stock advancing mechanisms.

The stock carriage mechanism of the multi-spindle CNC lathe 50 isillustrated in FIG. 29. The stock carriage tubes 602 and 606 of thestock carriage assembly 600 are supported on a carriage assembly 622.Rings 624 are provided at each end of a stock carriage housing 626.Rollers 628 are provided on the carriage assembly 622 and engage therings 624. By this means the carriage assembly 622 and therefore thestock carriage assembly 600 is adapted for revolution about the centralaxis 632 of the multi-spindle CNC lathe 50.

An indexing mechanism 640 for the multi-spindle CNC lathe 50 isillustrated in FIG. 30. A motor 642 drives an indexer 643 which has anoutput 644 that drives a drive pulley 646. A belt 648 extends around thedrive pulley 646 and functions to actuate a driven pulley 650 under theaction of the motor 642 and the indexer 643. The driven pulley 650 isconnected to a rotator plate 652 which is connected to the carriageassembly 622 by a plurality of threaded fasteners 658. Thus, uponactuation of the motor 642 and indexer 643, the carriage assembly 622and the stock carriage tubes mounted thereon are revolved around theaxis 632.

A spider 656 is mounted to the assembly 622 for rotation therewith underthe action of the motor 642 and the indexer 643. The spider 656comprises a plurality of pins 660 each having opposed spherical ends662. The spherical ends 662 of the pins 660 are received in bores 664,thereby accommodating a predetermined amount of misalignment between theassembly 622 and a connector 666 which is secured to the spindle carrier218 by means of a plurality of threaded fasteners 668. Thus, uponactuation the motor 642 functions not only to rotate the assembly 622but also to rotate the spindle carrier assembly 218 simultaneouslytherewith.

Operation

In the operation of the multi-spindle CNC lathe 50, one or more of theclosures 608 is disengaged to permit the insertion of stock into thetube 606 and the tube 602 of the stock carrier assembly. The glutactuator assembly 490 is then actuated to operate the dog 460 to openone or more of the collets 450. Stock is initially positioned manually.Thereafter, pressure of the coolant within the tubes 602 and 606 of thestock carrier assembly is selectively increased, whereupon the stock isadvanced through the corresponding collet 450 until it is properlypositioned.

Indexing of the stock relative to the tools of the multi-spindle CNClathe 50 begins with actuation of the piston 180 to move the ram 182rightwardly (FIG. 5) thereby disengaging the teeth 542 of the couplingportion 540 of the stock carrier 218 (FIG. 24) from the teeth 582 of thecoupling portion 582 which is secured to the frame 104 (FIG. 26). Theindexing motor 642 (FIG. 30) is then actuated to index the carriageassembly 622 and therefore the tubes 602 and 606, and also the stockcarrier 218 having the spindles 430 and the collets 450 mounted thereon.This action causes the stock, the tube 602 and 606, the spindles 430,and the collets 450 to revolve about the axis 632 of the multi-spindleCNC lathe 50 until the stock is properly positioned relative to theframe.

The internal slide assemblies 220 of the multi-spindle CNC lathe 50 aremounted on the guide body 308 which is secured to the wall 112 of thecasting 106 of the frame 104. Therefore, as the stock is indexed underthe action of the motor 642, the internal slide assemblies do not move,but instead remain stationary and in position to engage the nextindividual piece of stock which is aligned therewith.

Likewise, the external slide assemblies 330 are supported on supportbracket 332 which are secured to the wall 114 of the casting 108 of theframe 104 by threaded fasteners 334. Therefore, the external slidesassemblies 330 do not move as the stock is indexed under the action ofthe motor 642, but instead remained positioned for engagement with thenext piece of stock which is aligned therewith.

An important feature of the present invention comprises the fact thatthe external slide assemblies 330 are adapted to move the tools 336 notonly toward and away from, that is, perpendicular to the rotating stock,but also along the length of, that is parallel to the stock. The tools336 do not comprise forming tools, but instead comprise general purposemetal working tools which may be utilized to form any desired shape inthe external surfaces of the stock pieces. It is therefore not necessaryto remove and replace the tools 336 when adapting the multi-spindle CNClathe 50 of the present invention to the manufacture of a differentproduct.

This in turn means that the multi-spindle CNC lathe 50 of the presentinvention is readily adapted to the Just In Time, or JIT, manufacturingphilosophy in that the lathe 50 may be utilized to manufacture a smallnumber of parts and to have the parts available at the precise momentthat they are needed in subsequent manufacturing operations. Themulti-spindle CNC lathe 50 of the present invention is also readilyadapted to the Statistical Process Control, or SPC, manufacturingphilosophy whereby wearing of the tools utilized in the internal slideassemblies 220 and the external slide assemblies 330 is constantlymonitored and adjusted by actuating the slide assemblies 220 and 330 toassure manufacturing tolerances which are well within the acceptablerange.

After all of the tools comprising the internal slide assemblies 220 andall of the tools comprising the external slide assembly 330 havecompleted their respective functions, the tools are disengaged from therotating stock. At this point the piston 180 is actuated to disengagethe teeth 542 of the stock carrier 218 from the teeth 582, whereupon themotor 642 is actuated to index the stock into alignment with the nextsuccessive work station. As will be understood by those skilled in theart, one or more of the spindles comprising the multi-spindle CNC lathe50 comprises a cutoff station, wherein the finished work is disengagedfrom the stock. Upon cutoff, the stock is selectively advanced throughthe respective collets under the action of increased pressure in thecoolant in the associated tubes 602 and 606.

All of the component parts of the multi-spindle CNC lathe operate underthe control of the CNC system 56. In this manner there is facilitatedthe use of general purpose cutting tools, rather than forming tools,which in turn facilitates the JIT manufacturing philosophy. Likewise,the CNC system facilitates the SPC manufacturing philosophy byconstantly repositioning the cutting tools to accommodate wear.

Those skilled in the art will appreciate the fact that in the operationof the multi-spindle CNC lathe of the present invention, the two servomechanisms comprising each external slide assembly operatesimultaneously in order to form the complex configurations which aretypically fabricated on single spindle and multi-spindle legs.Preferably, each internal slide assembly 220 operates simultaneouslywith its corresponding external slide assembly 330 in order that themulti-spindle CNC lathe 50 can function at maximum efficiency. It willbe understood, however, that a particular internal slide assembly 220and its corresponding external slide assembly 330 can operatesequentially depending upon the requirements of particular applicationsof the invention.

Referring to FIG. 34, there is shown a length of bar stock 680 which issequentially formed into four entirely different piece parts 682, 684,686, and 688 utilizing the multi-spindle CNC lathe of the presentinvention. The piece parts 682, 684, 686, and 688 are formed at the samework station with the fabrication of the piece part 684 beginningimmediately after the completion of the piece part 682, etc. and withoutthe necessity of changing cutting tools or changing the set up of themulti-spindle CNC lathe 50. Referring to FIG. 35, a length of octagonalbar stock 690 is fabricated into entirely different piece parts 692 and694. Again, the manufacture of the piece part 694 begins immediatelyupon the completion of the piece part 692 without changing cutting toolsand without changing the set up of the multi-spindle CNC lathe 50.

Although preferred embodiments of the invention have been illustrated inthe accompanying Drawings and described in the foregoing DetailedDescription, it will be understood that the invention is not limited tothe embodiments disclosed but is capable of numerous rearrangements,modifications, and substitutions of parts and elements without departingfrom the spirit of the invention.

What is claimed is:
 1. A method of forming a single length of bar stockinto two different parts including the steps of:providing a length ofbar stock having an axis and a leading end including a first segmenthaving a leading and a trailing end and a second segment having aleading end and a trailing end, the trailing end of the first segmentbeing coincident with the leading end of the second segment; rotatingthe length of bar stock about its axis; providing a forming zone;selectively advancing the length of bar stock in a predetermineddirection along its axis until the first segment of the leading end ofthe length of bar stock is located in the forming zone; providing afirst single point cutting tool located in the forming zone; providing afirst servo mechanism for selectively advancing and retracting the firstcutting tool along a path parallel to the axis of the rotating length ofbar stock; providing a second single point cutting tool located in theforming zone; providing a second servo mechanism for selectivelyadvancing and retracting the second cutting tool radially relative tothe rotating length of bar stock; providing a third servo mechanism forselectively advancing and retracting the second cutting tool along apath parallel to the axis of the rotating bar stock; providing acomputer numeric control system for simultaneously operating the first,second, and third servo mechanisms; causing the computer numeric controlsystem to simultaneously operate the first, second, and third servomechanisms to advance and retract the first and second cutting tools inaccordance with a first predetermined sequence of instructions to formthe first segment of the leading end of the rotating length of the barstock into a first predetermined configuration; thereafter advancing thelength of bar stock along its axis until the second segment of theleading end of the length of bar stock is positioned in the formingzone; immediately thereafter causing the computer numeric control systemto simultaneously operate the first, second and third servo mechanismsto advance and retract the first and second cutting tools in accordancewith a second predetermined sequence of instructions to form the secondsegment of the leading end of the rotating length of bar stock into asecond predetermined configuration which is substantially different fromthe first predetermined configuration; foregoing steps being carried outwithout rotating either the first segment or the second segmentend-to-end.
 2. A method of forming a single length of bar stock into twodifferent parts including the steps of:storing two sets of operatinginstructions, the first set of operating instructions corresponding toconfiguration of a first part to be formed and the second part ofoperating instructions corresponding to the configuration of a secondpart to be formed, the configuration of the first and second parts to beformed to be substantially different; providing a length of bar stockhaving a longitudinal axis and a leading end comprising axially spacedfirst and second segments; rotating the length of bar stock about itslongitudinal axis; providing a forming zone; selectively advancing thelength of bar stock in a predetermined direction along its longitudinalaxis until the first segment of the leading end of the length of barstock is positioned in the forming zone; providing a first single pointcutting tool located in the forming zone; providing a servo mechanismfor selectively advancing and retracting the first single point cuttingtool along a path extending parallel to the axis of the rotating lengthof bar stock; providing a second single point cutting tool located inthe forming zone; providing a second servo mechanism for selectivelyadvancing and retracting the second single point cutting tool radiallyrelative to the rotating length of bar stock; providing a third servomechanism for selectively advancing and retracting the second singlepoint cutting tool along a path parallel to the axis of the rotatinglength of bar stock; simultaneously operating the first, second andthird servo mechanisms in accordance with the first set of instructionsto advance and retract the first and second single point cutting toolsin accordance therewith to form a first segment of the leading end ofthe rotating length of bar stock into the first predeterminedconfiguration; thereafter advancing the length of bar stock along itslongitudinal axis until the second segment of the leading end of thelength of bar stock is positioned in the forming zone; immediatelythereafter simultaneously operating the first, second, and third servomechanisms to advance and retract the first and second single pointcutting tools in accordance with the second set of instructions to formthe second segment of the leading end of the rotating length of barstock into the second configuration the foregoing steps being carriedout without rotating either the first segment or the second segment ofthe length of bar stock end-to-end.